The invention relates in general to the testing of fuel injectors and in particular to a method and apparatus for aligning and inserting a fuel injector in a test head.
Automatic testing machinery for fuel injectors utilize a moving conveyor on which are carried pucks. Each puck carries a fuel injector. The pucks are routed to various testing stations to assure that the newly manufactured fuel injector meets quality standards.
A puck with an injector carried therein is automatically placed under a test head. An actuator such as a hydraulic or pneumatic cylinder is located beneath the puck at its position beneath the test head. A fixed cone is mounted on the actuator for engaging the bottom of the puck. The fixed cone raises the puck upwards toward the test head so that the injector is inserted in the test head. An O-ring on the end of the injector provides a seal inside the test head. If the injector is not properly aligned with the test head, false leak readings may result. That is, the leakage may be occurring where the O-ring seals with the test head rather than in the injector itself. If that occurs, a perfectly good injector may be rejected because of a false leak reading.
Because of the speed at which the actuator raises the puck, the puck may not have enough time to center itself on the fixed cone before the injector engages the test head. The result is misalignment of the injector in the test head and/or damage to the top O-ring. At the last test head, the injector is fully manufactured and all other tests have been conducted. Therefore, to reject a good injector at the last test head is to lose all the parts and labor invested in a completely manufactured injector. If the rejection of good injectors at the last test head can be reduced, substantial savings can be realized.
It is an object of the invention to provide an apparatus and method for reducing the number of good injectors falsely rejected at a test head.
It is another object of the invention to provide an apparatus and method for reducing false leak test readings.
It is a further object of the invention to provide an apparatus and method which allows an injector to center itself as it is inserted in a test head.
It is yet another object of the invention to provide an apparatus and method to prevent damage to the top O-ring of an injector as it is inserted in a test head.
These and other objects of the invention are achieved by a floating locator cone assembly comprising a floating locator cone mount; a ball thrust bearing assembly inserted in the floating locator cone mount; and a floating locator cone inserted in the floating locator cone mount on top of the ball thrust bearing assembly.
Preferably, the floating locator cone assembly further comprises a catch cup inserted in the floating locator cone.
The floating locator cone mount includes a first bore extending partially therethrough to a radially inwardly formed step and an annular bore extending from the step partially through the floating locator cone mount; wherein the first bore has a larger diameter than the annular bore and a bottom of the annular bore provides a seat for the ball thrust bearing assembly. The floating locator cone mount defines a through hole concentric with the annular bore.
The ball thrust bearing assembly comprises a first washer disposed on the seat for the ball thrust bearing assembly, a ball thrust bearing disposed on the first washer and a second washer disposed on the ball thrust bearing.
The floating locator cone includes a generally cylindrical portion which is inserted in the first bore of the floating locator cone mount and rests on the second washer of the ball thrust bearing assembly. The floating locator cone also includes a generally converging through hole, wherein the catch cup is inserted in the generally converging through hole.
In addition, the floating locator cone includes a top portion which extends above the floating locator cone mount and wherein the top portion includes an external surface configured to engage a mating surface in a bottom of a puck.
Another aspect of the invention is a method of inserting an injector in a test head comprising inserting the injector in a puck; aligning the puck beneath the test head; engaging a bottom of the puck with a floating cone assembly; raising the puck upwards towards the test head; and inserting a top portion of the injector into the test head.
A further aspect of the invention is an apparatus for testing fuel injectors comprising a conveyor; at least one puck disposed on the conveyor; a fuel injector disposed in the at least one puck; a rotary table adjacent the conveyor for receiving pucks with fuel injectors contained therein from the conveyor; at least one test head located above the rotary table; an actuator located below the test head and the rotary table for raising and lowering a puck towards and away from the test head; and a floating cone assembly attached to the actuator, for engaging a bottom of a puck. The actuator may further comprise a spacer for vertical alignment of the floating cone assembly.
Further objects, features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the following drawing.